Vidson



(No Model.)

S. C. DAVIDSON. MULTITUBULAP. AIR HEATING APPARATUS.

190.593,989. Patented Nov. 23, 1897.

UNITED STATES PATENT Erica,

MULTITUBU LAR AIR-HEATING APPARATUS.

SPECFICATION forming part of Letters :Patent No. 593,989, dated November 23, 1897.

Application filed December 8, 1896. Serial No. 614,874. (Nomodel.) Patented in England September 21, 1895, No. 17,651; in India January 8, 1896, Noi 315,' and in Ceylon January 28,1896,No.489.

To @ZZ whom it may con/cern:

Be it known that I, SAMUEL CLELAND DA- vIDsoN, merchant, of Belfast, Ireland, have invented certain new and useful Improvements in Multitubular Air-Heating Apparatus, (for which I have obtained patents in Great Britain, No. 17,651, bearing date September 2l, 1895; in India, No. 315, of 1895, bearing date January 8, 1896, and in Ceylon, No. 489, bearing date January 28, 1896,) of which the following is a specification.

This invention has reference to multitubular air-heating apparatus in which the tubes are heated by live or exhaust steam passing through them.

In apparatus of this type where the tubes through which the steam passes are arranged to conduct the steam as a vertical flow and return current from an inlet-chamber in the base of one end of an inclosing compartment to an exhaust-chamber in the base of the other end the tubes are generally made of a U shape; but in such arrangements the elbows or bends of the outer rows of the U-shaped tubes must be carried over those of the inner rows. of tubes are employed the outer tubes are so much longer than the inner ones that they exhibit to the steam an equivalently greater amount of cooling and friction surface, and the various rows are consequently of relatively unequal efficiency in transmitting the heat from the steam passing throqgh to the air passing over them.

The objects of the hereinafter-described invention are to have the tubes so arranged that while any number of rows of tubes for the flow and return current of the steam can be employed that may be desirable all the iiow and all the return tubes shall be of equal length, and in order to provide for the difference of expansion between the flow andreturn tubes, (due to the average temperature of the flow-tubes being considerably higher than that of the return,) also to so arrange the flowtubes in a separate group from the returntubes that the expansion of the former, which is greater than the latter, owing to the temperature being higher, can take place independently of the tubes in the return group,

Therefore when several of these rows suitable material.

M stlat'thgreater expansion of the flow-tubes shall not put any detrimental strain on the jointing of either the flow'or return tubes in the perforations of the steam-receptacles with which they are connected.

According to my invention the multitubular air-heating apparatus comprises two distinctly separate sections or groups of perfectly straight tubes securely fitted at both ends into corresponding perforations in a pair of metal plates which form covers to troughshaped chambers or boxes, to which said plates are so secured that' these chambers or boxes form steam-chests at both ends of each group of tubes. One of these steam-chests thus formed is preferablyemployed as the base of its group of tubes, and for brevity of description I hereinafter refer to same as the lower steam-chest and to the steam-chest at the opposite end of same group of tubes as the F upper steam-chest. One of the groups of tubes is for flow of the steam-current and the other group for the return.

The two groups of tubes are placed side by side and the upper steam-chests are connected by a pipe of sufficiently large diameter to let the steam freely pass from the upper steam-chest of the one group of'tubes to that of the other, and in order to keepfthe lower steam-chests with respect to the upper ones a corresponding distance apart they are conhaust-pipe for carrying away the uncondensed steam so placed that it also acts as a drain-pipe for the condensed water, and into this pipe another drain-pipe of smaller diameter-is connected from the lower steam-chest of the flow group for relieving it also of condensed water. v

The two groups of flow and return pipes are inclosed in a casing of sheet-iron or other The air to be heated can be driven or drawnover and among the tubes by means of a fan or other air-propelling apparatus, and I preferably place the return IOO group of tubes next to the cold-air inlet and the flow group next the hot-air outlet from the casing.

' The exhaust or live steam, or partly both, on being admitted to the lower steam-chest of the iow group of tubes rises through these In the accompanying drawings of an apparatus constructed in accordance with my invention, Figure l is a longitudinal section on the line X X of Fig. 3. Fig. 2 is a cross-section on the line Y Y of Fig. 3. Fig. 3 is a sectional plan on the line Z Z of Fig. l.

On reference to the figures it will be seen that the heating apparatus is divided into two separate sections or groups of tubes, A representing those for the How-current of the steam and B those for the return.

C is the lower steam-chest, forming the base of the section or group of tubes A and into which the exhaust or live steam is adl mi-tted by the pipe A. The lower ends of the per steam-chest K of the section or group of tubes B.

L is the top cover of the steam-chest K, to

which the pipe I-l is also attached.

M is the perforated plate, forming the bottom of the chest K, and into which the upper ends of the tubes B are expanded.

N is the perforated plate, forming the top vcover of the lower steam-chest O, through which the lower ends of the tubes B pass and into which they are expanded.

`P is a small drain-pipe for the water conl densed in the dow-tubes A, and collecting in the lower steam-chest C to drain away into the exhaust and drain pipe R, by which the water and uncondensed steam is carried away from the lower steam-chest O.

`S is the sheet-iron casing, surrounding the tube-sections A and B.

T is the inlet for the cold air, an d U the outlet for the heated air, to which outlet may be attached pipes or other conduits for leading the heated air Wherever same may be required. y

The lower steam-chests C and O are kept their proper distance apart by the distancebolts V,

The working of the apparatus is as follows: Steam, either exhaust from an engine or live from a boiler, or partly both, is admit-ted to the lower steam-chest C by the pipe A', and

ilows up through the tubes A into the upper steam-chest F, passing from thence through the pipe H to the upper steam-chest K, then down it through the tubes B into the lower steam-chest O, iinally passing away by the drain and exhaust pipe R. The tubes in the group A from receiving the iirst ilow of the steam will of course be hotter than those in the group B, and their relative longitudinal expansion will be equivalently greater; but as the flow-tubes are all of equal length and the return-tubes are likewise all of equal length and as the steam is subjected to a mixing together in the upper steam-chests after leav-v ing the ilow group of tubes and before entering the return group all the tubes in each group have practically an equal expansion from being at about an equal average teml perature, and are therefore about equal in heat-transmitting ei'liciency.

As the pipe H, which connects the upper steam-chests F and K, and the distance-bolts which connect the lower steam-chests C and O do not form a rigidly hard connection between them, but allow of a slight movement of the one group independently of the other, the extra expansion of the flow group A can thus take place without in any way ,detrimentally affecting the jointing of the tubes in either group. The arrangement of the tubes in two groups of short straight lengths also combines with the above advantages a highlyeffective shape of casing for bringing the air intocontact with the hot tubes.

What l claim, and desire to secure by Letters Patent, i'sl. In lnultitubul'ar air-heating apparatus, in which the tubes are heated by steam passing through them, the combination of a series of straight tubes, all of equal length, for the iiow of the heating steam, a tube-plate at each end of said series of tubes and receiving said tubes, a supply steam-chest at the one end and a discharge steam-chest at the other end of said series of tubes, the inner wall of each of said steam-chests being the corresponding tube-plate; a second series of straight tubes all of equal length for the return of the heating steam, a tube-plate at each end of said second series of tubes, saidtubeplates receiving said' tubes and being independent of the tube-plates of the flow series of tubes, a supply steam-chest at the one end y and a discharge steam-chest at the other end of said second series of tubes, the inner Wall of each of said steam-chests being the corresponding tube-plate, and a steam-pipe yieldingly connected to and communicating between the discharge steam-chest of the ser-ies of How-tubes and the supply steam-chest of the series of return-tubes, and conducting the steam from said discharge steam-chest and yielding to the differences in expansion between said chests to said supply steam-chest, all substantially as hereinbelore described and shown, whereby the tubes in cach series are free to expand and contract in their sep- IOO IIOI

IZO

arate tube-plates independently of the expansion of the tubes of the other series in their tube-plates, as and for the purpose set forth.

2. In multitubular air-heating apparatus, in which the tubes are heated by steam passing through them, a separate series of straight tubes of equal length for the inflow of the heating steam, and a separate series of straight tubes of equal length for the outflow of the steam,in combination with separate and independent tube-plates to which the two series of tubes are respectively connected, steamchests of which said tube-plates form part, the chests at the discharge end of the inflowtubes and at the receiving ends of the outiowf tubes having sheet-metal covers, and a pipe conducting the steam from the outflow end of the first series of tubes to the inflow end of the second series, and connected to said sheetmetal covers,whereby the pipe and covers can yield and expansion and contraction of said two series of tubes under variations of ternperature can take place independently of each 3. In a m ultitubular air-heating apparatus, in which the tubes are heated by steam passing through them, the combination of the inflow-tubes A, the outflow-tubes B, the steamchests C and F with which the inlet and delivery ends of said tubes A respectively conimunicate, the steam-chests K and O with which the inlet and ldelivery ends of said tubes B respectively communicate, the steampipe I-I communicating between said chests F and K, said chests F and K separate and independently movable under expansion of their tubes, the steam-inlet pipe A', the eX- haust and drain pipe R, the distance-bolts V between and connecting said chests C and O,

and the casing S inclosing both said inflow and outiow tubes and their chests and having air-inlet T and air-outlet U, all substantially as set forth and shown.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

v SAMUEL CLELAND DAVIDSON. Witnesses:

GEORGE GooLD WARD, XVILLIAM FREW. 

